Solid-state imaging device and method for producing the same

ABSTRACT

A solid-state imaging device includes a plurality of vertical charge transferring portions, and a horizontal charge transferring portion connected to at least one end of each of the vertical charge transferring portions. A vertical transfer channel region of a first conductivity, an element isolating region of a second conductivity and a vertical well region of the second conductivity that constitute the vertical charge transferring portion are extended up to the connection portion between the vertical charge transferring portions and the horizontal charge transferring portion, and the end portions of the extended regions of the vertical transfer channel region of the first conductivity and the vertical well region of the second conductivity on the side of the horizontal charge transferring portion are positioned more on the side of the horizontal charge transferring portion than the end portion of the final vertical transfer electrode on the side of the horizontal charge transferring portion, and are positioned within 1.5 μm from the end portion of the element isolating region of the second conductivity on the side of the horizontal charge transferring portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solid-state imaging device includinga plurality of vertical charge transferring portions and a horizontalcharge transferring portion connected to one end or both ends of thevertical charge transferring portions, and a method for producing thesame.

2. Description of the Related Art

An interline-transfer solid-state imaging device includes a plurality ofphotoelectric exchanging portions arranged in a matrix, a plurality ofarrays of vertical charge transferring portions arranged correspondingto each array of the photoelectric exchanging portions, a horizontalcharge transferring portion electrically connected to one end of eachvertical charge transferring portion, and an output circuit portionconnected to one end of the horizontal charge transferring portion. Insuch a solid-state imaging device, signal charges generated in thephotoelectric exchanging portions are transferred in the verticaldirection by the vertical charge transferring portions and then to thehorizontal charge transferring portion. In the horizontal transferringportion, the signal charges are transferred in the horizontal direction(direction orthogonal to the transfer direction of the vertical chargetransferring portions) to the output circuit portion.

The conventional structure of the connection portion between thevertical charge transferring portions and the horizontal chargetransferring portion of such a solid-state imaging device is described,for example, in JP 5-29599A and JP 10-135439 A. FIGS. 19A and 19B areschematic views showing the structure in the vicinity of the connectionportion between the vertical charge transferring portions and thehorizontal charge transferring portion of the conventionalinterline-transfer solid-state imaging device. FIG. 19A is a plan viewand FIG. 19B is a cross-sectional view taken along line A-A′ of the FIG.19A.

In the vertical charge transferring portion 501, a vertical p-type well503 is formed in a surface layer portion of an n⁻⁻-type semiconductorsubstrate 502, and an n-type vertical transfer channel 504 is formed inthe surface layer portion of the vertical p-type well 503. A pluralityof vertical transfer electrodes 507, 509 a, and 509 b and a finalvertical transfer electrode 508 are formed on the surface of then⁻⁻-type semiconductor substrate 502 via a gate insulating film 506. Thevertical transfer electrodes are wired such that a clock pulse φV1, φV2,φV3, or φV4 is applied to the vertical transfer electrodes. In thevertical charge transferring portion 501, a p⁺-type element separatingregion 505 for electrically separating between the vertical transferchannels 504 is formed.

In the horizontal charge transferring portion 510, a horizontal p-typewell 511 is formed in a surface layer portion of the n⁻⁻-typesemiconductor substrate 502, and an n-type horizontal transfer channel512 is formed in the surface layer portion of the horizontal p-type well511. A plurality of first horizontal transfer electrodes 513 a and 513 bare formed on the surface of the n⁻⁻-type semiconductor substrate 502via the gate insulating film 506. Furthermore, an n⁻-type potentialbarrier region 514 is formed in a gap between the first horizontaltransfer electrodes and a gap between the final vertical transferelectrode 508 and the first horizontal transfer electrode 513 a, andsecond horizontal transfer electrodes 515 a and 515 b are formed on thepotential barrier region 514 via the gate insulating film 506. Thehorizontal transfer electrodes are wired such that a clock pulse φH1 orφH2 is applied to the horizontal transfer electrodes.

In the connection portion between the vertical charge transferringportion 501 and horizontal charge transferring portion 510, the p⁺-typeelement separating region 505 extends from the side of the verticalcharge transferring portion 501. In this connection portion, thehorizontal transfer channel 512 extends from the horizontal chargetransferring portion 510 side. The portion of the horizontal transferchannel 512 that extends in the connection portion is placed between thep⁺-type element separating regions 505. On the other hand, the verticaltransfer channel 504 does not extend in the connection portion, and theend portion 521 thereof on the side of the horizontal chargetransferring portion substantially matches the end portion of the finalvertical transfer electrode 508. In this connection portion, the n⁻-typepotential barrier region 514 is formed on a portion corresponding to theboundary between the vertical transfer channel 504 and the horizontaltransfer channel 512.

The channel width of the vertical transfer channel 504 is narrower thanthat of the horizontal transfer channel 512, and therefore the impurityconcentration of the vertical transfer channel 504 is higher than thatof the horizontal transfer channel 512 in order to ensure the amount oftransfer signals. Since the horizontal charge transferring portion 510has a higher transfer frequency than that of the vertical chargetransferring portion 501, the p-type impurity concentration of thehorizontal p-type well 511 is lower than that of the vertical p-typewell 503 so as to intensify the transfer electric field.

Next, the charge transfer operation from the vertical chargetransferring portion to the horizontal charge transferring portion willbe described with reference to FIGS. 20 and 21. FIG. 21 shows an exampleof clock pulses that are applied to the electrodes of the verticalcharge transferring portions and the horizontal charge transferringportion. FIG. 20 is a diagram showing a potential distribution duringcharge transfer from the vertical charge transferring portion to thehorizontal charge transferring portion when they are driven by the clockpulses shown in FIG. 21. In the potential diagram, it is assumed thatthe downward potential is positive and charges are held in a hatchedportion (which also applies to the following).

At a time t1, the signal charge 517 in the vertical charge transferringportion 501 is accumulated below the first vertical transfer electrode507 and the second vertical transfer electrode 509 b to which a highvoltage V_(VH) is applied. Next, at a time t2, the clock pulse φV4changes from V_(VL) to V_(VH), and the clock pulse φV2 changes fromV_(VH) to V_(VL), so that a part of the signal charge 517 is started tobe transferred from the vertical charge transferring portion 501 to thehorizontal charge transferring portion 510. Then, at a time t3, the dockpulse φV1 changes from V_(VL) to V_(VH), and the dock pulse φV3 changesfrom V_(VH) to V_(VL), so that the signal charge 517 further istransferred from the vertical charge transferring portion 501 to thehorizontal charge transferring portion 510. At a time t4, the clockpulse φV2 changes from V_(VL) to V_(VH), and the clock pulse φV4 changesfrom V_(VH) to V_(VL), and thus the operation of the transfer of thesignal charge 517 from the vertical charge transferring portion 501 tothe horizontal charge transferring portion 510 is completed. At thispoint, the signal charge 517 is accumulated in the first horizontaltransfer electrode 513 a to which V_(HH) of the horizontal chargetransferring portion 510 is applied. Furthermore, the next signal charge518 has been transferred up to a portion below the first verticaltransfer electrode 507 and the second vertical transfer electrode 509 ato which a high voltage V_(VH) is applied. At a time t5, the clock pulseφV3 changes from V_(VL) to V_(VH), and the clock pulse φV1 changes fromV_(VH) to V_(VL), so that the next signal charge 518 is transferred upto a portion below the first vertical transfer electrode 507 and thesecond vertical transfer electrode 509 b to which a high voltage V_(VH)is applied. Thereafter, the horizontal charge transferring portion 510is operated so that transfer pulses φH1 and φH2 that have oppositephases to each other are applied to the horizontal transfer electrodes,and the signal charge 517 is transferred in the horizontal chargetransferring portion. Thereafter, by repeating this operation, thesignal charge 517 is transferred in the vertical charge transferringportion 501 and the horizontal charge transferring portion 510.

As shown in FIG. 20, in the connection portion between the verticalcharge transferring portion and the horizontal charge transferringportion, a potential barrier 519 is present because of the potentialbarrier region 514 formed below the second horizontal transfer electrode515 a, and further a potential barrier 520 is present as a result of anarrow channel effect caused by the element isolating region 505 of thevertical charge transferring portion. Therefore, the reverse transfer ofthe signal charge from the horizontal charge transferring portion to thevertical charge transferring portion is prevented.

Next, a method for producing the solid-state imaging device will bedescribed. FIGS. 22A, 22B, 23A, 23B, 24A, 24B, 25A and 25B are views forillustrating a method for producing the solid-state imaging device.FIGS. 22A, 23A, 24A and 25A show portions corresponding to the crosssections taken along line A-A′ of FIG. 19A, and FIGS. 22B, 23B, 24B and25B show portions corresponding to the cross sections taken along lineB-B′ of FIG. 19A.

First, as shown in FIGS. 22A and 22B, a protective film 526 is formed onthe surface of the n⁻⁻-type semiconductor substrate 502, and the elementisolating region 505 is formed by implanting ions of p-type impuritiessuch as boron in a region other than the regions in which a verticaltransfer channel and a horizontal transfer channel are to be formed inthe surface layer portion of the n⁻⁻-type semiconductor substrate 502.Then, a first photoresist film 534 is formed on the surface of theprotective film 526, and the first photoresist film 534 is removed fromthe regions in which a vertical transfer channel and a horizontaltransfer channel are to be formed, and then a p-type region 524 isformed by implanting ions of p-type impurities such as boron in thesurface layer portion of the n⁻⁻-type semiconductor substrate 502. Ann-type region 525 is formed by implanting ions of n-type impurities suchas phosphorus or arsenic in the surface layer portion of the p-typeregion 524.

Then, after the first photoresist film 534 is removed entirely, as shownin FIGS. 23A and 23B, a second photoresist film 528 is formed on thesurface of the protective film, and the second photoresist film 528 isremoved from the region in which a vertical transfer channel is to beformed, and then a vertical p-type well 503 is formed by implanting ionsof p-type impurities such as boron in substantially the same depth asthe p-type region 524, and a vertical transfer channel 504 is formed byimplanting ions of n-type impurities such as phosphorus or arsenic insubstantially the same depth as the n-type region 525. Here, theportions of the p-type region 524 and the n-type region 525 in which thevertical p-type well 503 and the vertical transfer channel 504 are notformed serve as the horizontal p-type well 511 and the horizontaltransfer channel 512, respectively.

Then, after the second photoresist film 528 and the protective film 526are removed entirely, as shown in FIGS. 24A and 24B, the gate insulatingfilm 506 is formed, and transfer electrodes 507, 508, 513 a and 513 b ofthe first layer are formed on the gate insulating film 506. Then, athird photoresist film 529 is formed on the surface thereof. After thisfilm is removed from the region on the side of the horizontal transferchannel such that the boundary is on the final vertical transferelectrode 508, the n⁻-type potential barrier region 514 is formed byimplanting ions of p-type impurities such as boron.

Then, after the third photoresist film 529 is removed entirely, as shownin FIGS. 25A and 25B, an interlayer insulating film 527 is formed aroundthe transfer electrodes 507, 508, 513 a and 513 b of the first layer,and then transfer electrodes 509 a, 509 b, 515 a and 515 b of the secondlayer are formed. Wiring is performed by metal films such as aluminum ortungsten such that clock pluses φV1, φV2, φV3, and φV4 can be applied tothe vertical transfer electrode 509 a, 507, 509 b and 508, and thatclock pluses φH and φH2 can be applied to a pair of horizontal transferelectrodes 513 a and 515 a, and a pair of horizontal transfer electrodes513 b and 515 b. Thus, the conventional solid-state imaging device canbe produced.

However, in the conventional solid-state imaging device, the chargetransfer from the vertical charge transferring portion to the horizontalcharge transferring portion cannot be performed smoothly in asufficiently short time as the miniaturization of pixels, the high-speeddriving of the vertical charge transferring portion and the low voltagedriving of the horizontal charge transferring portion are promoted, andabnormal display such as appearance of vertical lines generally calledblack line defects occurs, or the transfer efficiency is deterioratedsignificantly. The reasons why these problems occur will be describedwith reference to FIG. 20.

In the conventional solid-state imaging device, with the miniaturizationof pixels, the channel width of the vertical transfer channel 504 shouldbe decreased, so that it is necessary to increase the n-type impurityconcentration of the vertical transfer channel 504 in order to ensurethe amount of transfer charges. On the other hand, it is not necessaryto decrease the channel width of the horizontal transfer channel 512, sothat it is not necessary to increase the n-type impurity concentrationof the horizontal transfer channel 512.

Furthermore, in the conventional solid-state imaging device, the endportion 521 of the vertical transfer channel 504 on the side of thehorizontal charge transferring portion is formed so as to substantiallymatch the end portion of the final vertical transfer electrode 508, andthe potential barrier region 514 and the horizontal transfer channel 512are formed more on the side of the horizontal charge transferringportion than the end portion of the final vertical transfer electrode508. In other words, the vertical transfer channel 504 having a highn-type impurity concentration is formed below the final verticaltransfer electrode 508, and the horizontal transfer channel 512 having alow n-type impurity concentration is formed in a region below the firsthorizontal transfer electrode 513 a and the second horizontal transferelectrode 515 a in the connection portion between the vertical chargetransferring portion 501 and the horizontal charge transferring portion510.

Therefore, when the n-type impurity concentration difference between thevertical transfer channel 504 and the horizontal transfer channel 512 isincreased or the low voltage driving of the horizontal chargetransferring portion is promoted, the channel potential below the secondhorizontal transfer electrode 515 a and the first horizontal transferelectrode 513 a (to which V_(HH) is applied) in the connection portionis formed in a smaller depth than the channel potential below the finalvertical transfer electrode 508 (to which V_(VH) is applied). Thus, thetransfer barrier 523 is formed at times t2 and t3 in FIG. 20. As aresult, all the signal charges 517 a and 517 b left in the verticalcharge transferring portion 501 cannot be transferred to the horizontalcharge transferring portion 510 in a short time from a time t4 to a timeof the start of operation of the horizontal charge transferring portion,and untransferred signal charges 522 are generated and abnormal displaysuch as the appearance of vertical lines called black line defects mayoccur.

In order not to generate the transfer barrier 523 as described above,the final vertical transfer electrode 508 is formed independently ofother vertical transfer electrodes to which φV4 is applied, and a clockpulse φV4′ with a lower voltage than the high level voltage V_(VH) canbe applied to the final vertical transfer electrode 508. In this case,however, poor transfer occurs anew from the second vertical transferelectrode 509 b to the final vertical transfer electrode 508, and aseparate power source for generating the clock pulse φV4′ is required sothat a driving circuit becomes complicated.

In the method for producing the conventional solid-state imaging deviceas described above, with the miniaturization of pixels, a variation inthe amount of transfer charge in the vertical charge transferringportion is increased because of displacement of mask alignment. Thereason why this problem occurs will be described with reference to FIG.22.

The vertical transfer channel 504 and the vertical p-type well 503 areformed, as described above, by implanting ions of n-type impurities andp-type impurities after the first photoresist film 534 is patterned andremoved [FIGS. 22A and 22B], then by implanting ions of n-typeimpurities and p-type impurities after the second photoresist film 528is patterned and removed [FIGS. 23A and 23B]. Thus, the verticaltransfer channel 504 and the vertical p-type well 503 are formed in twophotoresist processes, so that the displacement of the mask alignmentbetween the first photoresist process and the second photoresist processmay cause variation in the width of the vertical transfer channel 504 orthe vertical p-type well 503 to be formed. As a result, in particular,as the size of the pixels is decreased, a variation in the amount oftransfer charge in the vertical charge transferring portion isincreased.

SUMMARY OF THE INVENTION

Therefore, with the foregoing in mind, it is an object of the presentinvention to provide a solid-state imaging device that can ensure asufficient amount of transfer charge in each of the vertical chargetransferring portions and reduce sufficiently untransferred signalcharges that occur when transferring the signal charges from each of thevertical charge transferring portions to the horizontal chargetransferring portion and thus can be provided with good displaycharacteristics, even if the miniaturization of pixels or the lowvoltage driving in the horizontal charge transferring portion arepromoted, and a method for producing such a solid-state imaging devicewith a high precision.

In order to achieve the above object, a solid-state imaging device ofthe present invention includes a plurality of vertical chargetransferring portions, and a horizontal charge transferring portion thatis connected to at least one end of each of the vertical chargetransferring portions, receives charges transferred from each of thevertical charge transferring portions and transfers the charges. Each ofthe vertical charge transferring portions includes a vertical transferchannel region of a first conductivity, an element isolating region of asecond conductivity formed so as to be adjacent to the vertical transferchannel region of the first conductivity, a plurality of verticaltransfer electrodes and a final vertical transfer electrode formed onthe vertical transfer channel region of the first conductivity, and avertical well region of the second conductivity formed below thevertical transfer channel region of the first conductivity. Thehorizontal charge transferring portion includes a horizontal transferchannel region of a first conductivity, and a plurality of horizontaltransfer electrodes formed on the horizontal transfer channel region ofthe first conductivity, and a horizontal well region of the secondconductivity formed below the horizontal transfer channel region of thefirst conductivity. In a connection portion between each of the verticalcharge transferring portions and the horizontal charge transferringportion, the vertical transfer channel region of the first conductivity,the element isolating region of the second conductivity and the verticalwell region of the second conductivity extend from each of the verticalcharge transferring portions, and a part of the horizontal transferelectrodes is overlapped on a portion of the vertical transfer channelregion of the first conductivity that extends in the connection portion.The end portions of the portions of the vertical transfer channel regionof the first conductivity and the vertical well region of the secondconductivity that extend in the connection portion on the side of thehorizontal charge transferring portion are positioned more on the sideof the horizontal charge transferring portion than an end portion of thefinal vertical transfer electrode on the side of the horizontal chargetransferring portion, and are positioned within 1.5 μm from the endportion of the element separating isolating region of the secondconductivity on the side of the horizontal charge transferring portion.

Furthermore, a first production method of the present invention is amethod for producing the solid-state imaging device of the presentinvention and includes forming an ion implantation blocking film on asemiconductor substrate; forming a first photoresist film on the ionimplantation blocking film, patterning the first photoresist film andthe ion implantation blocking film such that the first photoresist filmand the ion implantation blocking film are left on a region to be formedinto an element isolating region of a second conductivity and areremoved from a region to be formed into a vertical transfer channelregion of a first conductivity and a horizontal transfer channel regionof the first conductivity; forming the vertical transfer channel regionof the first conductivity and the horizontal transfer channel region ofthe first conductivity by implanting ions of impurities of the firstconductivity in a surface layer of the semiconductor substrate, andforming a vertical well region of the first conductivity and ahorizontal well region of the first conductivity by implanting ions ofimpurities of the second conductivity below the vertical transferchannel region of the first conductivity and the horizontal transferchannel region of the first conductivity, using the first photoresistfilm and the ion implantation blocking film as a mask; removing thefirst photoresist film and then forming a second photoresist film on thesemiconductor substrate; patterning the second photoresist film suchthat the second photoresist is left on the horizontal transfer channelregion of the first conductivity and removed from the vertical transferchannel region of the first conductivity; and implanting further ions ofimpurities of the first conductivity in the vertical transfer channelregion of the first conductivity, using the second photoresist film anddie ion implantation blocking film as a mask.

Furthermore, a second production method of the present invention is amethod for producing the solid-state imaging device of the presentinvention and includes forming an ion implantation blocking film on asemiconductor substrate; forming a first photoresist film on the ionimplantation blocking film; patterning the first photoresist film andthe ion implantation blocking film such that the first photoresist filmand the ion implantation blocking film at left on a region to be formedinto an element isolating region of a second conductivity and areremoved from a region to be formed into a vertical transfer channelregion of a first conductivity and a horizontal transfer channel regionof the first conductivity; forming the vertical transfer channel regionof the first conductivity and the horizontal transfer channel region ofthe first conductivity by implanting ions of impurities of the firstconductivity in a surface layer of the semiconductor substrate using thefirst photoresist film and the ion implantation blocking film as a mask,removing the first photoresist film and then forming a secondphotoresist film on the semiconductor substrate; patterning the secondphotoresist film such that the second photoresist is left on thehorizontal transfer channel region of the first conductivity and removedfrom at least the vertical transfer channel region of the firstconductivity; forming a vertical well region of the second conductivityby implanting further ions of impurities of the first conductivity inthe vertical transfer channel region and implanting ions of impuritiesof the second conductivity below the vertical transfer channel region,using the second photoresist film and die ion implantation blocking filmas a mask; removing the second photoresist film and the ion implantationblocking film and then forming a third photoresist film on thesemiconductor substrate; patterning the third photoresist film such thatthe third photoresist film is left at least on the vertical transferchannel region of the first conductivity and removed from the horizontaltransfer channel region of the first conductivity; and forming avertical well region of the second conductivity by implanting ions ofimpurities of the second conductivity below the horizontal transferchannel region, using the third photoresist film as a mask.

Further, a third production method of the present invention is a methodfor producing the solid-state imaging device of the present inventionand includes forming a first photoresist film on a semiconductorsubstrate; patterning the first photoresist film such that the firstphotoresist film is left on a region to be formed into an elementisolating region of a second conductivity and is removed from a regionto be formed into a vertical transfer channel region of a firstconductivity and a horizontal transfer channel region of the firstconductivity; forming the vertical transfer channel region of the firstconductivity and the horizontal transfer channel region of rite firstconductivity by implanting ions of impurities of the first conductivityin a surface layer of the semiconductor substrate using the firstphotoresist film as a mask, and forming a vertical well region of thefirst conductivity and a horizontal well region of the firstconductivity by implanting ions of impurities of the second conductivitybelow the vertical transfer channel region of the first conductivity andthe horizontal transfer channel region of the first conductivity;removing the first photoresist film and then forming a secondphotoresist film on the semiconductor substrate; patterning the secondphotoresist film such that the second photoresist is left on a region tobe formed into an element isolating region of the second conductivityand the horizontal transfer channel region of the first conductivity andis removed from the horizontal transfer channel region of the firstconductivity, and implanting further ions of impurities of the secondconductivity in the horizontal transfer channel region of the firstconductivity, using the second photoresist film as a mask

In the third production method, it is preferable that the method furtherincludes implanting ions of impurities of the first conductivity in thehorizontal well region of the second conductivity, using the secondphotoresist film as a mask.

According to the solid-state imaging device of the present invention,even if the difference in the n-type impurity concentration between eachof the vertical transfer channels and the horizontal transfer channel isincreased in order to increase the amount of transfer charge of each ofthe vertical charge transferring portions or the low voltage driving ofthe horizontal charge transferring portion is promoted, the signalcharges can be transferred to the horizontal charge transferring portionsmoothly in a short time. Consequently, the miniaturization of pixels,the high-speed driving of each of the vertical charge transferringportions and the low voltage driving of the horizontal chargetransferring portion can be promoted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an example of a solid-state imagingdevice of a first embodiment.

FIGS. 2A and 2B are schematic views showing an example of the structurein the vicinity of the connection portion between the vertical chargetransferring portion and the horizontal charge transferring portion inthe solid-state imaging device of the first embodiment; and FIG. 2A is aplan view thereof and FIG. 2B is a cross-sectional view taken along lineA-A′ of FIG. 2A.

FIG. 3 is a schematic diagram showing the potential distribution duringcharge transfer from the vertical charge transferring portion to thehorizontal charge transferring portion of the solid-state imaging deviceof the first embodiment.

FIG. 4 is a schematic diagram showing the channel potential distributionfrom the vertical charge transferring portion to the horizontal chargetransferring portion when the solid-state imaging device of the firstembodiment of the present invention is driven.

FIG. 5 is a graph showing the results of analyzing the potential barrierand the potential depression occurring between the vertical chargetransferring portion and the horizontal charge transferring portion whenthe position of the end portion of the vertical transfer channel isshifted with respect to the end portion of the element separatingregion.

FIGS. 6A and 6B are schematic views illustrating a first example of amethod for producing the solid-state imaging device of the firstembodiment; and FIG. 6A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 6B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 7A and 7B are schematic views illustrating the first example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 7A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 7B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 8A and 8B are schematic views illustrating the first example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 8A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 8B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 9A and 9B are schematic views illustrating the first example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 9A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 9B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 10A and 10B are schematic views illustrating a second example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 10A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 10B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 11A and 11B are schematic views illustrating the second example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 11A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 11B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 12A and 12B are schematic views illustrating the second example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 12A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 12B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 13A and 13B are schematic views illustrating the second example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 13A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 13B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 14A and 14B are schematic views illustrating the second example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 14A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 14B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 15A and 15B are schematic views illustrating a third example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 15A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 15B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 16A and 16B are schematic views illustrating the third example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 16A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 16B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 17A and 17B are schematic views illustrating the third example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 17A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 17B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 18A and 18B are schematic views illustrating the third example ofthe method for producing the solid-state imaging device of the firstembodiment; and FIG. 18A shows a portion corresponding to the crosssection taken along line A-A′ of FIG. 2A, and FIG. 18B shows a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

FIGS. 19A and 19B are schematic views showing the structure in thevicinity of the connection portion between the vertical chargetransferring portion and the horizontal charge transferring portion in aconventional solid-state imaging device; and FIG. 19A is a plan viewthereof and FIG. 19B is a cross-sectional view taken along line A-A′ ofFIG. 19A.

FIG. 20 is a schematic diagram showing the potential distribution duringcharge transfer from the vertical charge transferring portion to thehorizontal charge transferring portion of the conventional solid-stateimaging device.

FIG. 21 is an example of clock pulses that are applied to the electrodesof the vertical charge transferring portion and the horizontal chargetransferring portion.

FIGS. 22A and 22B are schematic views illustrating a method forproducing the conventional solid-state imaging device; and FIG. 22Ashows a portion corresponding to the cross section taken along line A-A′of FIG. 19A, and FIG. 22B shows a portion corresponding to the crosssection taken along line B-B′ of FIG. 19A.

FIGS. 23A and 23B are schematic views illustrating the method forproducing the conventional solid-state imaging device; and FIG. 23Ashows a portion corresponding to the cross section taken along line A-A′of FIG. 19A, and FIG. 23B shows a portion corresponding to the crosssection taken along line B-B′ of FIG. 19A.

FIGS. 24A and 24B are schematic views illustrating the method forproducing the conventional solid-state imaging device; and FIG. 24Ashows a portion corresponding to the cross section taken along line A-A′of FIG. 19A, and FIG. 24B shows a portion corresponding to the crosssection taken along line B-B′ of FIG. 19A.

FIGS. 25A and 25B are schematic views illustrating the method forproducing the conventional solid-state imaging device; and FIG. 25Ashows a portion corresponding to the cross section taken along line A-A′of FIG. 19A, and FIG. 25B shows a portion corresponding to the crosssection taken along line B-B′ of FIG. 19A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the solid-state imaging device of the present invention, asdescribed above, the vertical transfer channel region of a firstconductivity, the element isolating region of a second conductivity andthe vertical well region of the second conductivity are extended to theconnection portion between each of the vertical charge transferringportions and the horizontal charge transferring portion, and the endportions of the extended portions of the vertical transfer channelregion of the first conductivity and the vertical well region of thesecond conductivity on the side of the horizontal charge transferringportion are positioned more on the side of the horizontal chargetransferring portion than the end portion of the final vertical transferelectrode on the side of the horizontal charge transferring portion, andare positioned within 1.5 μm from the end portion of the elementisolating region of the second conductivity on the side of thehorizontal charge transferring portion. Thus, even if the difference inthe n-type impurity concentration between tile vertical transfer channeland the horizontal transfer channel is increased in order to increasethe amount of transfer charge of each of the vertical chargetransferring portions or the low voltage driving of the horizontalcharge transferring portion is promoted, signal charges can betransferred to the horizontal charge transferring portion smoothly in ashort nine. Therefore, the miniaturization of pixels, the high-speeddriving of each of the vertical charge transferring portions and the lowvoltage driving of the horizontal charge transferring portion can bepromoted further while ensuring good display characteristics.

In the solid-state imaging device, it is preferable that the horizontaltransfer channel region of the first conductivity is formed so as tohave a lower impurity concentration than that of the vertical transferchannel region of the first conductivity. According to this preferableexample, even if the channel width of the vertical transfer channelregion is decreased with the miniaturization of pixels, a sufficientamount of transfer signals can be ensured.

In the solid-state imaging device, it is preferable that the horizontaltransfer channel region of the first conductivity is formed so as tohave a larger diffusion depth than that of the vertical transfer channelregion of the first conductivity. According to this preferable example,the electric field in the horizontal transfer channel region from thehorizontal transfer electrodes extends up to a deep portion, andtherefore the transfer electric field is intensified and the transferefficiency in the horizontal charge transferring portion is improvedfurther.

In the solid-state imaging device, it is preferable that the horizontalwell region of the second conductivity is formed so as to have a lowerimpurity concentration than that of the vertical well region of thesecond conductivity. According to this preferable example, the electricfield in the horizontal transfer channel region from the horizontaltransfer electrodes extends up to a deep portion, and therefore thetransfer electric field is intensified and the transfer efficiency inthe horizontal charge transferring portion is improved further. Inaddition, since the channel potential of the horizontal transfer channelregion is formed deeper than that of the vertical transfer channelregion, signal charges can be transferred from the vertical chargetransferring portion to the horizontal charge transferring portion evenmore smoothly.

In the solid-state imaging device, it is preferable that the horizontalwell region of the second conductivity is formed so as to have a largerdiffusion depth than that of the vertical well region of the secondconductivity. According to this preferable example, the electric fieldin the horizontal transfer channel region from the horizontal transferelectrodes extends up to a deep portion, and therefore the transferelectric field is intensified and the transfer efficiency in thehorizontal charge transferring portion is improved further. In addition,since the channel potential of the horizontal transfer channel region isformed deeper than that of the vertical transfer channel region, signalcharges can be transferred from the vertical charge transferring portionto the horizontal charge transferring portion even more smoothly.

In the solid-state imaging device, it is preferable that the impurityconcentrations of the vertical transfer channel region of the firstconductivity and the horizontal transfer channel region of the firstconductivity are set such that, with respect to the horizontal transferelectrodes arranged so as to overlap the vertical transfer channelregion of the first conductivity in the connection portion, a channelpotential of the horizontal transfer channel region of the firstconductivity positioned below the horizontal transfer electrodes isdeeper than that of the vertical transfer channel region of the firstconductivity positioned below the horizontal transfer electrodes.According to this preferable example, signal charges can be transferredfrom the vertical charge transferring portion to the horizontal chargetransferring portion even more smoothly.

First Embodiment

An example of a solid-state imaging device of a first embodiment of thepresent invention will be described FIG. 1 is a schematic view showingan example of a solid-state imaging device of a first embodiment. FIGS.2A and 2B are schematic views showing an example of the structure in thevicinity of the connection portion between the vertical chargetransferring portion and the horizontal charge transferring portion inthe solid-state imaging device of the first embodiment; and FIG. 2A is aplan view thereof and FIG. 2B is a cross-sectional view taken along lineA-A′ of FIG. 2A.

As shown in FIG. 1, this solid-state imaging device includes a pluralityof photoelectric exchanging portions 130 arranged in a matrix, aplurality of arrays of vertical charge transferring portions 101arranged corresponding to each array of the photoelectric exchangingportions 130, a horizontal charge transferring portion 110 electricallyconnected to one end of each vertical charge transferring portion 101,and an output circuit portion 131 connected to one end of the horizontalcharge transferring portion 110.

As shown in FIGS. 2A and 2B, in the vertical charge transferring portion101, a vertical p-type well 103 is formed in a surface layer portion ofan n⁻⁻-type semiconductor substrate 102, and an n-type vertical transferchannel 104 is formed in the surface layer portion of the verticalp-type well 103. Furthermore, a p⁺-type element isolating region 105 isformed between the vertical transfer channels 104. A plurality ofvertical transfer electrodes 107, 109 a and 109 b and a final verticaltransfer electrode 108 are formed on the vertical transfer channel 104via a gate insulating film 106. The vertical transfer electrodes arewired such that a clock pulse φV1, φV2, φV3, or φV4 is applied to thevertical transfer electrodes.

In the horizontal charge transferring portion 110, a horizontal p-typewell 111 is formed in a surface layer portion of the n⁻⁻-typesemiconductor substrate 102, and an n-type horizontal transfer channel112 is formed in the surface layer portion of the horizontal p-type well111. A plurality of first horizontal transfer electrodes 113 a and 113 bare formed on the horizontal transfer channel 112 via the gateinsulating film 106. Furthermore, an n⁻-type potential barrier region114 is formed in a gap between the first horizontal transfer electrodes,and second horizontal transfer electrodes 115 a and 115 b are formed onthe potential barrier region 114 via the gate insulating film 106. Thehorizontal transfer electrodes are wired such that a clock pulse φH1 orφH2 is applied to the horizontal transfer electrodes.

The channel width of the vertical transfer channel 104 is narrower thanthat of the horizontal transfer channel 112, and therefore the n-typeimpurity concentration of the vertical transfer channel 104 is a higherthan that of the horizontal transfer channel 112 in order to ensure theamount of transfer signals. Since the horizontal charge transferringportion 110 has a higher transfer frequency than that of the verticalcharge transferring portion 10 1, the p-type impurity concentration ofthe horizontal p-type well 111 is lower than that of the vertical p-typewell 103 so as to intensify the transfer electric field.

In the connection portion between each of the vertical chargetransferring portions and the horizontal charge transferring portion,the vertical p-type well 103, the p+-type element isolating region 105and the vertical transfer channel 104 extend from the vertical chargetransferring portion side. In this connection portion, the p⁺-typeelement isolating region 105 is farmed so as to be overlapped on the endportion of the second horizontal transfer electrode 115 b on the side ofthe vertical charge transferring portion. The vertical transfer channel104 is formed so as to be overlapped on the end portions of the firsthorizontal transfer electrode 113 a and the second horizontal transferelectrode 115 a that receive the charges transferred from the verticalcharge transferring portion 101 on the side of the vertical chargetransferring portion. Furthermore, in this connection portion, then-type potential barrier region 114 is formed in a gap between the finalvertical transfer electrode 108 and the first horizontal transferelectrode 113 a and the second horizontal transfer electrode 115 a isoverlapped on the potential barrier region 114 via the gate insulatingfilm 106.

In this solid-state imaging device, the vertical p-type well 103, thevertical transfer channel 104 and the p⁺-type element isolating region105 extend in the connection portion between vertical chargetransferring portion 101 and the horizontal charge transferring portion110, as described above, and the positions of the end portions 121 ofthe vertical p-type well 103 and the vertical transfer channel 104 areadjusted so as to substantially march the position of the end portion116 off the p-type element isolating region 105 on the side of thehorizontal charge transferring portion.

In other words, the vertical transfer channel 104 and the verticalp-type well 103 are formed both in a region below the final verticaltransfer electrode 108 and a region below the first horizontal transferelectrode 113 a and the second horizontal transfer electrode 115 a inthe connection portion. More specifically, the region below the finalvertical transfer electrode 108 and the region below the firsthorizontal transfer electrode 113 a in the connection portion havesubstantially the same impurity concentration.

Next, the charge transfer operation from the vertical chargetransferring portion to the horizontal charge transferring portion ofthe solid-state imaging device will be described.

FIG. 21 shows an example of a clock pulse that is applied to eachelectrode of the vertical charge transferring portion and the horizontalcharge transferring portion. In this FIG. 21, φV1 to φV4 are transferpulses applied to the vertical transfer electrodes, and φH1 and φH2 aretransfer pulses applied to the horizontal transfer electrodes. In eachpulse, V_(VH) and V_(HH) indicate high level voltages, and V_(VL) andV_(HL) indicate low level voltages. FIG. 3 is a schematic diagramshowing the potential distribution during charge transfer from thevertical charge transferring portion to the horizontal chargetransferring portion when driven by the clock pulses shown in FIG. 21.

At a time t1, the signal charge 117 in the vertical charge transferringportion 101 is accumulated below the first vertical transfer electrode107 and the second vertical transfer electrode 109 b to which a highvoltage V_(VH) is applied. Next, at a time t2, the clock pulse φV4changes from V_(VL) to V_(VH), and the clock pulse φV2 changes fromV_(VH) to V_(VL), so that all the signal charge 117 except the signalcharge 117 a left in a gap between the final vertical transfer electrode108 and the second vertical transfer electrode 109 b are transferredfrom the vertical charge transferring portion 101 to the horizontalcharge transferring portion 110. Then, at a time t3, the clock pulse φV1changes from V_(VL) to V_(VH), and the clock pulse φV3 changes fromV_(VH) to V_(VL), so that the left signal charge 117 a also istransferred from the vertical charge transferring portion 101 to thehorizontal charge transferring portion 110. Thus, all the signal charge117 is accumulated in the first horizontal transfer electrode 113 a towhich V_(HH) of the horizontal charge transferring portion 110 isapplied. At a time t4, the clock pulse φV2 changes from V_(VL) toV_(VH), and the clock pulse φV4 changes from V_(VH) to V_(VL), and thenext signal charge 118 has been transferred up to a portion below thefirst vertical transfer electrode 107 and the second vertical transferelectrode 109 a to which a high voltage V_(HH) is applied. At a time t5,the dock pulse φV3 changes from V_(VL) to V_(VH), and the clock pulseφV1 changes from V_(VH) to V_(VL), so that the next signal charge 118 istransferred up to a portion below the first vertical transfer electrode107 and the second vertical transfer electrode 109 b to which a highvoltage V_(VH) is applied. Thereafter, the horizontal chargetransferring portion 110 is operated so that transfer pulses φH1 and φH2that have opposite phases to each other are applied to the horizontaltransfer electrodes, and the signal charge 117 is transferred in thehorizontal charge transferring portion. Thereafter, by repeating thisoperation, the signal charge 117 is transferred in the vertical chargetransferring portion 101 and the horizontal charge transferring portion110.

As shown in FIG. 3, in the connection portion between each of thevertical charge transferring portions and the horizontal chargetransferring portion, a potential barrier 119 is present because of thepotential barrier region 114 formed below the second horizontal transferelectrode 115 a, and further a potential battier 120 is present as aresult of a narrow channel effect caused by the element isolating region105 of the vertical charge transferring portion. Therefore, the reversetransfer of the signal charge from the horizontal charge transferringportion to the vertical charge transferring portion is prevented.

Next, the effect achieved by such a solid-state imaging device will bedescribed with reference to FIGS. 2 and 3, as described above, thissolid-state imaging device is formed such that the transfer channel 104and the element isolating region 105 extend in the connected potionbetween the vertical charge transferring portion 101 and the horizontalcharge transferring potion 110, and the position of the end portion 121of the vertical transfer channel 104 substantially matches the positionof the end portion of the element isolating region 105. In other words,the region below the final vertical transfer electrode 108 and theregion below the first horizontal transfer electrode 113 a in theconnection portion have substantially the same impurity concentration.

Therefore, even if the difference in the n-type impurity concentrationbetween the vertical transfer channel 104 and the horizontal transferchannel 112 is increased in order to increase the amount of transfercharge of the vertical charge transferring portion 101 or the lowvoltage driving of the horizontal charge transferring portion 110 ispromoted, the channel potential below the second horizontal transferelectrode 115 a and the first horizontal transfer electrode 113 a (towhich V_(HH) is applied) in the connection portion is deeper than thechannel potential below the final vertical transfer electrode 108 (towhich V_(VH) is applied) (see reference numeral 132 of FIG. 3).Therefore, a transfer barrier (reference numeral 523 of FIG. 20) doesnot occur as in the conventional solid-state imaging device, and duringtimes t2 to t3, the signal charge 117 is transferred to the horizontalcharge transferring portion 110 smoothly. Consequently, the occurrenceof abnormal display such as appearance of vertical lines called blackline defects can be suppressed. Therefore, the miniaturization ofpixels, the high-speed driving of the vertical charge transferringportion and the low voltage driving of the horizontal chargetransferring portion can be promoted while ensuring good displaycharacteristics.

The more the n-type impurity concentration of the vertical transferchannel 104 is higher than that of horizontal transfer channel 112, thelower the potential barrier 120 generated by the narrow channel effectof the element isolating region 105 of the vertical charge transferringportion is. Therefore, it is preferable to set the n-type impurityconcentration of the vertical transfer channel 104 to be higher thanthat of horizontal transfer channel 112 within the range in which thepotential barrier 120 does not appear.

In the connection portion, it is preferable that the end portion 121 ofthe vertical transfer channel 104 and the cad portion 116 of the p⁺-typeelement isolating region 105 are formed such that the positions thereofsubstantially match each other. However, since the channel potentialfrom the vertical charge transferring portion 101 to the horizontalcharge transferring portion 110 changes so as to be gradually deeperbecause of the narrow channel effect, if the position of the end portion121 of the vertical transfer channel 104 is within this range of thechanging region 133 of this channel potential, the potential depressionor the generation of a barrier can be suppressed sufficiently, and it ispossible to achieve the above-described effect More specifically, theend portion 121 of the vertical transfer channel 104 can be positionedmore on the side of the horizontal charge transferring portion than theend portion of the final vertical transfer electrode 108 on the side ofthe horizontal charge transferring portion and be positioned within 1.5μm from the end portion 116 of the p⁺-type element isolating region 105.

Next, the above-described effect will be described more specifically,using an example of the forming conditions and the driving conditions ofthe solid-state imaging device.

The channel width of the vertical transfer channel 104 of thesolid-state imaging device is, for example, 0.7 μm, so as to be adaptedfor miniaturization of pixels, one side of which is 3 μm or less. Thechannel width of the horizontal transfer channel 112 is irrelevant tothe miniaturization of pixels and can be, for example, 30 μm. Thus, thechannel width of the vertical transfer channel 104 is smaller than thatof the horizontal transfer channel 112, so that the n-type impurityconcentration of the vertical transfer channel 104 is higher than thatof the horizontal transfer channel 112 in order to ensure the amount oftransfer signals. For example, the n-type impurity concentration of thevertical transfer channel 104 can be 2×10¹⁷ cm⁻³, and the n-typeimpurity concentration of the horizontal transfer channel 112 can be1.5×10¹⁷ cm⁻³. Furthermore, the horizontal charge transferring portion110 has a higher transfer frequency than that of the vertical chargetransferring portion 101, so that the p-type impurity concentration ofthe horizontal p-type well 111 is lower than that of the vertical p-typewell 103 in order to intensity the transfer electric field. For example,the p-type impurity concentration of the vertical p-type well 103 can be2×10¹⁶ cm⁻³, and the p-type impurity concentration of the horizontalp-type well 111 can be 1.5×10¹⁶ cm⁻³. The n⁻-type potential barrierregion 114 formed in a gap between the first horizontal transferelectrodes, and a gap between the final vertical transfer electrode 108and the first horizontal transfer electrode 113 a can be formed byimplanting ions of p-type impurities such as boron in a dose amount of5.0×10¹¹ cm⁻² onto the vertical transfer channel having theaforementioned impurity concentration.

In each pulse shown in FIG. 21, for the voltages φV1 to φV4 and φH1 andφH2, for example, V_(VH)=0V, V_(HH)=3V, V_(VL)=−8V, and V_(HL)=0V.

FIG. 4 shows the channel potential distribution from each of thevertical charge transferring portions to the horizontal chargetransferring portion of the solid-state imaging device that is formedunder these conditions and driven. FIG. 4 shows the channel potentialdistributions in the following cases: the position of the end portion121 of the vertical transfer channel is shifted by 2 μm to the side ofthe vertical charge transferring portion with respect to the position ofthe end portion 116 of the element isolating region (1), the positionsare matched (II), and the position of the end portion 121 of thevertical transfer channel is shifted by 2 μm to the side of thehorizontal charge transferring portion.

When the position of the end portion 121 of the vertical transferchannel is matched to the position of the end portion 116 of the elementisolating region (II), the channel potential below the final verticaltransfer electrode 108 (to which V_(VH)=0V is applied) is about 6Vbecause of the narrow channel effect, the channel potential of a region(potential barrier region 114) positioned below the second horizontaltransfer electrode 115 a (to which V_(HH)=3V is applied) in theconnection portion is about 7V because of the narrow channel effect, andthe channel potential of a region (vertical transfer channel 104)positioned below the first horizontal transfer electrode 113 a (to whichV_(HH)=3V is applied) in the connection portion is about 8V because ofthe narrow channel effect. On the other hand, the channel potential of aregion (horizontal transfer channel 112) positioned below the firsthorizontal transfer electrode 113 a (to which V_(HH)=3V is applied) inthe horizontal charge transferring portion is about 10V because there isalmost no narrow channel effect. Thus, the channel potential is farmedso as to become gradually deeper front the final vertical transferelectrode 108 to the horizontal transfer channel 112, so that the signalcharge can be transferred from the vertical charge transferring portion101 to the horizontal charge transferring portion 110 smoothly in ashort time.

Furthermore, when the position of the end portion 121 of the verticaltransfer channel is shifted to the side of the vertical chargetransferring portion with respect to the end portion 116 of the elementisolating region, a potential barrier tends to occur, and when it isshifted to the side of the horizontal charge transferring portion, apotential depression tends to occur (I and III).

FIG. 5 is a graph showing the results of analyzing the magnitude of thepotential barrier and the potential depression occurring between thevertical charge transferring portion and the horizontal chargetransferring portion by simulation when the position of the end portion121 of the vertical transfer channel is shifted to the side of thevertical charge transferring portion and the side of the horizontalcharge transferring portion with respect to the end portion 116 of theelement isolating region 105. As shown in these results, when the shiftbetween the position of the end portion 121 of the vertical transferchannel and the end portion 116 of the element isolating region iswithin 1.5 μm or less, substantially no potential barrier or potentialdepression occur, and the occurrence of abnormal display such asappearance of vertical lines called black line defects can besuppressed.

Second Embodiment

Next, a first example of a method for producing the solid-state imagingdevice will be described. FIGS. 6A, 6B, 7A, 7B, 8A, 8B, 9A and 9B areviews illustrating a method for producing the solid-state imagingdevice. FIGS. 6A, 7A, 8A, and 9A show a portion corresponding to thecross section taken along line A-A′ of FIG. 2A, and FIGS. 6B, 7B, 8B,and 9B show a portion corresponding to the cross section taken alongline B-B′ of FIG. 2A.

As shown in FIGS. 6A and 6B, a protective film 126 such as an oxide filmis formed on the surface of the n⁻⁻-type semiconductor substrate 102. Anion implantation blocking film 135 such as a nitride film is formed onthe protective film 126, and a first photoresist film 134 is formed onthe surface of the ion implantation blocking film 135. Then, the firstphotoresist film 134 and the ion implantation blocking film 135 arepatterned and removed such that the first photoresist film 134 and theion implantation blocking film 135 are removed from the region where avertical transfer channel and a horizontal transfer channel are to beformed, and are left on the portion to be formed into the elementisolating region. Thereafter, a p-type region 124 is formed byimplanting ions of p-type impurities such as boron into the surfacelayer portion of the n⁻⁻-type semiconductor substrate 102, and an n-typeregion 125 is formed by implanting ions of n-type impurities such asphosphorus or arsenic into the surface layer portion of the p-typeregion 124.

Then, the first photoresist film 134 is removed entirely. In this case,the ion implantation blocking film 135 is left as it is on thesubstrate. Then, a second photoresist film 128 is formed on the surfaceof the protective film 126 and the ion implantation blocking film 135.Thereafter, as shown in FIGS. 7A and 7B, the second photoresist film 128is patterned and removed such that the second photoresist film 128 isremoved from at least on the region where a vertical transfer channel isto be formed and is left on the region where a horizontal transferchannel is to be formed. Using as a mask the second photoresist film 128and the ion implantation blocking film 135 that are left, a verticalp-type well 103 is formed by implanting ions of p-type impurities suchas boron in substantially the same depth as the p-type region 124, and avertical transfer channel 104 is formed by implanting ions of n-typeimpurities such as phosphorus or arsenic in substantially the same depthas the n-type region 125. The portions of the p-type region 124 and then-type region 125 in which the vertical p-type well 103 and the verticaltransfer channel 104 are not formed serve as a horizontal p-type well111 and a horizontal transfer channel 112, respectively.

At this point, the shift between the positions of the boundary betweenthe vertical transfer channel and the horizontal transfer channel (theend portion 121 of the vertical transfer channel on the side of thehorizontal charge transferring portion) and the boundary between thevertical p-type well and the horizontal p-type well (the end portion 137of the vertical p-type well on the side of the horizontal chargetransferring portion), and the position of the end portion of the regionto be formed into the element isolating region 105 on the side of thehorizontal charge transferring portion (corresponding to referencenumeral 116 of FIG. 7B) is adjusted so as to be within 1.5 μm.

Then, after the second photoresist film 128 and the ion implantationblocking film 135 are removed entirely, as shown in FIGS. 8A and 8B, theelement isolating region 105 is formed by implanting ions of p-typeimpurities such as boron into the region other than the verticaltransfer channel and the horizontal transfer channel of the surfacelayer portion of the n⁻⁻-type semiconductor substrate 102. After theprotective film 126 is removed entirely, a gate insulating film 106 isformed on the surface, and transfer electrodes 107, 108. 113 a, and 113b of the first layer are formed on the gate insulating film 106.Furthermore, a third photoresist film 129 is formed on the surface andthen removed from the region on the side of the horizontal transferchannel so as to have the end portion on the final vertical transferelectrode 108. Thereafter, an n⁻-type potential barrier region 114 isformed by implanting ions of p-type impurities such as boron.

Then, after the third photoresist film 129 is removed entirely, as shownin FIGS. 9A and 9B, an interlayer insulating film 127 is formed aroundthe transfer electrodes 107, 108, 113 a, and 113 b of the first layer,and transfer electrodes 109 a, 109 b, 115 a, and 115 b of the secondlayer are formed. Wiring is performed with metal films such as aluminumor tungsten such that the clock pulses φV1, φV2, φV3, and φV4 areapplied to the vertical transfer electrodes 109 a, 107, 109 b, and 108,respectively, and the clock pulses φH1 and φH2 are applied to a pair ofhorizontal transfer electrodes 113 a and 115 a and a pair of horizontaltransfer electrodes 113 b and 115 b, respectively. Thus, the solid-stateimaging device of the first embodiment is produced.

Next, the effects achieved by this method for producing a solid-stateimaging device will be described with reference to FIGS. 6A, 6B, 7A and7B. In this production method, the vertical transfer channel 104 and thevertical p-type well 103 are formed in the following manner as describedabove: The first photoresist film 134 and the ion implantation blockingfilm 135 are patterned and removed, and then ions of n-type impuritiesand p-type impurities are implanted [FIGS. 6A and 6B]. Then, after thesecond photoresist film 128 is formed, the second photoresist film 128is removed from at least the region where a vertical transfer channel isto be formed, and then ions of p-type impurities and n-type impuritiesare implanted, using as a mask the second photoresist film 128 and theion implantation blocking film 135 that are patterned and left [FIGS. 7Aand 7B]. Thus, the vertical transfer channel 104 and the vertical p-typewell 103 in the method for producing the solid-state imaging device ofthe second embodiment are formed by two operations of n-type impurityand p-type impurity ion implantation, respectively, in the same manneras in the conventional production method. However, in this case, ionsare implanted using as a mask the ion implantation blocking film 135that has been patterned and removed in one photoresist process, andtherefore a positional shift in the horizontal direction or a widthspread of the implanted region between the first and the second ionimplantation does not occur, which stabilizes the widths of the verticaltransfer channel 104 and the vertical p-type well 103 to be formed. As aresult, even if the miniaturization of pixels is promoted, a variationin the amount of transfer charges in the vertical charge transferringportion and poor transfer of signal charges from the vertical chargetransferring portion to the horizontal charge transferring portion canbe suppressed.

Third Embodiment

Next, a second example of the method for producing the solid-stateimaging device of the first embodiment will be described. FIGS. 10A,10B, 11A, 11B, 12A, 12B, 13A, 13B and 14A and 14B are views illustratinga method for producing the solid-state imaging device. FIGS. 10A, 11A,12A, 13A, and 14A show a portion corresponding to the cross sectiontaken along line A-A′ of FIG. 2A, and FIGS. 10B, 11B, 12B, 13B, and 14Bshow a portion corresponding to the cross section taken along line B-B′of FIG. 2A.

First, as shown in FIGS. 10A and 10B, a protective film 226 such as anoxide film is formed on the surface of the n⁻⁻-type semiconductorsubstrate 202. An ion implantation blocking film 235 such as a nitridefilm is formed on the protective film 226, and a first photoresist film234 is formed on the surface of the ion implantation blocking film 235.Then, the first photoresist film 234 and the ion implantation blockingfilm 235 are patterned and removed such that the first photoresist film234 and the ion implantation blocking film 235 are removed from theregion where a vertical transfer channel and a horizontal transferchannel are to be formed, and are left on the portion to be formed intothe element isolating region. Thereafter, an n-type region 225 is formedby implanting ions of n-type impurities such as phosphorus or arsenicinto the surface layer portion of the n⁻⁻-type semiconductor substrate202.

Then, the first photoresist film 234 is removed entirely. In this case,the ion implantation blocking film 235 is left as it is on thesubstrate. Then, a second photoresist film 228 is formed on the surfaceof the protective film 226 and the ion implantation blocking film 235.Thereafter, as shown in FIGS. 11A and 11B, the second photoresist film228 is patterned and removed such that the second photoresist film 228is removed from at least on the region where a vertical transfer channelis to be formed and is left on the region where a horizontal transferchannel is to be formed. Using as a mask the second photoresist film 228and the ion implantation blocking film 235 that are left, a verticalp-type well 203 is formed by implanting ions of p-type impurities suchas boron below the n-type region 225, and a vertical transfer channel204 is formed by implanting ions of n-type impurities such as phosphorusor arsenic in substantially the same depth as the n-type region 225. Theportion of the n-type region 225 in which the vertical transfer channel204 is not formed serves as a horizontal transfer channel 212.

At this point, the shift between the position of the boundary betweenthe vertical transfer channel and the horizontal transfer channel (theend portion 221 of the vertical transfer channel on the side of thehorizontal charge transferring portion) and the position of the endportion of the region to be formed into the p⁺-type element isolatingregion 205 on the side of the horizontal charge transferring portion(corresponding to reference numeral 216 of FIG. 11B) is adjusted so asto be within 1.5 μm.

Then, after the second photoresist film 228 and the ion implantationblocking film 235 are removed entirely, a third photoresist film 229 isformed on the surface of the protective film 226. Thereafter, as shownin FIGS. 12A and 12B, the third photoresist film 229 is patterned andremoved such that the third photoresist film 229 is left at least on thevertical transfer channel and removed from on the horizontal transferchannel. A horizontal p-type well 211 is formed by implanting ions ofp-type impurities such as boron below the horizontal transfer channel212, using as a mask the third photoresist film 229 that is left.

At this point, the shift between the position of the boundary betweenthe vertical p-type well and the horizontal p-type well (the end portion237 of the vertical p-type well on the side of the horizontal chargetransferring portion) and the position of the end portion of the regionto be formed into the p⁺-type element isolating region 205 on the sideof the horizontal charge transferring portion (corresponding toreference numeral 216 of FIG. 13B) is adjusted so as to be within 1.5μm.

Then, after the third photoresist film 229 is removed entirely, as shownin FIGS. 1 3A and 133, the element isolating region 205 is formed byimplanting ions of p-type impurities such as boron onto the region otherthan the vertical transfer channel and the horizontal transfer channelof the surface layer portion of the n⁻⁻-type semiconductor substrate202. After the protective film 226 is removed entirely, a gateinsulating film 206 is formed on the surface, and transfer electrodes207,208, 213 a, and 213 b of the first layer are formed on the gateinsulating film 206, Furthermore, a fourth photoresist film 236 isformed on the surface and then removed the region on the side of thehorizontal transfer channel so as to have the end portion o finalvertical transfer electrode 208. Thereafter, an n⁻-type potentialbarrier region 214 is formed by implanting ions of p-type impuritiessuch as boron.

Then, after the fourth photoresist film 236 is removed entirely, asshown in FIGS. 14A and 14B, an interlayer insulating film 227 is formedaround the transfer electrodes 207, 208, 213 a, and 213 b of the firstlayer, and transfer electrodes 209 a, 209 b, 215 a, and 215 b of thesecond layer are formed. Wiring is performed with metal films such asaluminum or tungsten such that the clock pulses φV1, φV2, φV3, and φV4are applied to the vertical transfer electrodes 209 a, 207, 209 b, and208, respectively, and the clock pulses φH1 and φH2 are applied to apair of horizontal transfer electrodes 213 a and 215 a and a pair ofhorizontal transfer electrodes 213 b and 215 b, respectively. Thus, thesolid-state imaging device of the first embodiment is produced.

Next, the effects achieved by this method for producing a solid-stateimaging device will be described with reference to FIGS. 10A, 10B, 11A,11B, 12A and 12B. In this production method as well as the productionmethod of the second embodiment, the vertical transfer channel 204 isformed by two operations of ion implantation using as a mask the ionimplantation blocking film 235 that has been patterned and removed inone photoresist process, and therefore a positional shift in thehorizontal direction or a width spread of the implanted region betweenthe first and the second n-type impurity ion implantation does notoccur, which stabilizes the width of the vertical transfer channel 204to be formed (FIGS. 10A, 10B, 11A and 11B). As a result, even if theminiaturization of pixels is promoted, a variation in the amount oftransfer charges in the vertical charge transferring portion and poortransfer of signal charges from the vertical charge transferring portionto the horizontal charge transferring portion can be suppressed.

Furthermore, in the method for producing the solid-state imaging deviceof the third embodiment, the vertical p-type well 203 and the horizontalp-type well 211 are formed by the photoresist process and the ionimplantation process that are independent from each other, and thereforeeach p-type well can be designed optimally (FIGS. 11A, 11B, 12A and12B). For example, the vertical p-type well 203 having a highconcentration can be formed in a shallow region of the n⁻⁻-typesemiconductor substrate 202, and the horizontal p-type well 211 having alow concentration can be formed in a deep region of the n⁻⁻-typesemiconductor substrate 202. Thus, an increase of the amount of signalcharges and a reduction of smear in the vertical charge transferringportion 201 can be achieved together with the improvement of the chargetransfer efficiency in the horizontal charge transferring portion 210.

Fourth Embodiment

Next, a third example of the method for producing the solid-stateimaging device of the first embodiment will be described. FIGS. 15A,15B, 16A, 16B, 17A, 17B, 18A and 18B are views illustrating a method forproducing the solid-state imaging device. FIGS. 15A, 16A, 17A, and 18Ashow a portion corresponding to the cross section taken along line A-A′of FIG. 2A, and FIGS. 15B, 16B, 17B, and 18B show a portioncorresponding to the cross section taken along line B-B′ of FIG. 2A.

As shown in FIGS. 15A and 15B, a protective film 326 such as an oxidefilm is formed on the surface of the n⁻⁻-type semiconductor substrate302. A first photoresist film 334 is formed on the surface of theprotective film 326. Then, the first photoresist film 334 is patternedand removed such that the first photoresist film 334 is left on theregion to be formed into art element isolating region and is removedfrom on the region where a vertical transfer channel and a horizontaltransfer channel are to be formed. Thereafter, a p-type region 324 isformed by implanting ions of p-type impurities such as boron into thesurface layer portion of the n⁻⁻-type semiconductor substrate 302, andan n-type region 325 is formed by implanting ions of n-type impuritiessuch as phosphorus or arsenic into the surface layer portion of thep-type region 324.

Then, the first photoresist film 334 is removed entirely, and a secondphotoresist film 328 is formed on the surface of the protective film326. As shown in FIGS. 16A and 168, the second photoresist film 328 ispatterned and removed such that the second photoresist film 328 is lefton the regions to be farmed into an element isolating region and avertical channel region, and is removed from the region where ahorizontal transfer channel is to be formed. Using as a mask the secondphotoresist film 328 that is left, a horizontal p-type well 311 having alow concentration is formed by implanting ions of n-type impurities suchas phosphorus or arsenic in substantially the same depth as the p-typeregion 324, and a horizontal transfer channel 312 having a lowconcentration is formed by implanting ions of p-type impurities such asboron in substantially the same depth as the n-type region 325. Theportions of the p-type region 324 and the n-type region 325 in which thehorizontal p-type well 311 and the horizontal transfer channel 312 arenot formed serve as a vertical p-type well 303 and a vertical transferchannel 304, respectively.

At this point, the shift between the positions of the boundary betweenthe vertical transfer channel and the horizontal transfer channel (theend portion 321 of the vertical transfer channel on the side of thehorizontal charge transferring portion) and the boundary between thevertical p-type well and the horizontal p-type well (the end portion 337of the vertical p-type well on the side of the horizontal chargetransferring portion), and the position of the end portion of the regionto be formed into the p⁺-type element isolating region 305 on the sideof the horizontal charge transferring portion (corresponding toreference numeral 316 of FIG. 17B) is adjusted so as to be within 1.5μm.

Then, after the second photoresist film 328 is removed entirely, asshown in FIGS. 17A and 17B, the element isolating region 305 is formedby implanting ions of p-type impurities such as boron into the regionother than the vertical transfer channel and the horizontal transferchannel of the surface layer portion of the n⁻⁻-type semiconductorsubstrate 302. After the protective film 326 is removed entirely, a gateinsulating film 306 is formed on the surface, and transfer electrodes307, 308, 313 a, and 313 b of the first layer are formed on the gateinsulating film 306. Furthermore, a third photoresist film 329 is formedon the surface and then removed from the region on the side of thehorizontal transfer channel so as to have the end portion on the finalvertical transfer electrode 308. Thereafter, art n⁻-type potentialbarrier region 314 is formed by implanting ions of p-type impuritiessuch as boron.

Then, after the third photoresist film 329 is removed entirely, as shownin FIGS. 18A and 18B, an interlayer insulating film 327 is formed aroundthe transfer electrodes 307, 308, 313 a, and 313 b of the first layer,and transfer electrodes 309 a, 309 b, 315 a, and 315 b of the secondlayer are formed. Wiring is performed with metal films such as aluminumor tungsten such that the clock pulses φV1, φV2, φV3, and φV4 areapplied to the vertical transfer electrodes 309 a, 307, 309 b, and 308,respectively, and the clock pulses φH1 and φH2 are applied to a pair ofhorizontal transfer electrodes 313 a and 315 a and a pair of horizontaltransfer electrodes 313 b and 315 b, respectively. Thus, the solid-stateimaging device of the first embodiment is produced.

Next, the effects achieved by this method for producing a solid-stateimaging device will be described with reference to FIGS. 15A and 15B. Inthis production method, as described above, the vertical transferchannel 304 and the vertical p-type well 303 are formed by only oneoperation of ion implantation of n-type impurities and p-typeimpurities, respectively, using as a mask the first photoresist film 334that has been patterned and removed [FIGS. 15A and 15B], and therefore apositional shift in the horizontal direction or a width spread of theimplanted region between the first and the second ion implantation isnot caused by the first and the second ion implantation for forming thevertical transfer channel and the vertical p-type well, and the width ofthe regions where the vertical transfer channel 304 and the verticalp-type well 303 are formed becomes stable. As a result, even if theminiaturization of pixels is promoted, a variation in the amount oftransfer charges in the vertical charge transferring portion and poortransfer of signal charges from the vertical charge transferring portionto the horizontal charge transferring portion can be suppressed.

Furthermore, in the method for producing a solid-state imaging device ofthe fourth embodiment, unlike the production methods of the second andthe third embodiments, there is no need for forming the ion implantationblocking film, and therefore it is possible to shorten the productionprocess. Furthermore, etching damage caused by patterning and removingthe ion implantation blocking film, or a variation in the amount of ionimplantation caused by varied films that are left can be suppressed, sothat a solid-state imaging device having a low dark current and a smallvariation in the amount of transfer charge can be achieved.

In the first to fourth embodiments, the p-type impurity concentration isdifferent between the vertical p-type well and the horizontal p-typewell, but this is illustrative, and the two p-type wells may have thesame impurity concentration.

In addition, the horizontal transfer channel is formed in substantiallythe same depth as that of the vertical transfer channel, but this isillustrative, and the horizontal transfer channel may be formed deeperthan the vertical transfer channel.

Furthermore, in the connection portion between the vertical chargetransferring portion and the horizontal charge transferring portion, thepotential barrier region is formed in a region corresponding to a gapbetween the final vertical transfer electrode and the first horizontaltransfer electrode, but this is illustrative and no potential barrierregion may be formed.

Furthermore, the vertical charge transferring portion and the horizontalcharge transferring portion include transfer electrodes having a twolayered structure, but the present invention is not limited thereto. Forexample, the transfer electrodes have a single layer structure or amultilayer structure including three or more layers.

The present invention has been described by taking as an example aninterline-transfer solid-state imaging device having a horizontal chargetransferring portion electrically connected to one end of verticalcharge transferring portions. However, the present invention is notlimited thereto, and for example, the present invention also can applyto solid-state imaging devices having other systems such as a frametransfer type or solid-state imaging devices having horizontal chargetransferring portions electrically connected to both ends of verticalcharge transferring portions.

The invention may be embodied in other forms without departing from thespirit or essential characteristics thereof The embodiments disclosed inthis application are to be considered in all respects as illustrativeand not limiting. The scope of the invention is indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

1. A solid-state imaging device comprising a plurality of verticalcharge transferring portions, and a horizontal charge transferringportion that is connected to at least one end of the vertical chargetransferring portions, receives charges transferred from the verticalcharge transferring portions and transfers the charges, wherein each ofthe vertical charge transferring portions includes a vertical transferchannel region of a first conductivity, an element isolating region of asecond conductivity formed so as to be adjacent to the vertical transferchannel region of the first conductivity, a plurality of verticaltransfer electrodes and a final vertical transfer electrode formed onthe vertical transfer channel region of the first conductivity, and avertical well region of the second conductivity formed below thevertical transfer channel region of the first conductivity, thehorizontal charge transferring portion includes a horizontal transferchannel region of a first conductivity, and a plurality of horizontaltransfer electrodes formed on the horizontal transfer channel region ofthe first conductivity, and a horizontal well region of the secondconductivity formed below the horizontal transfer channel region of thefirst conductivity, in a connection portion between each of the verticalcharge transferring portions and the horizontal charge transferringportion, the vertical transfer channel region of the first conductivity,the element isolating region of the second conductivity and the verticalwell region of the second conductivity extend from each of the verticalcharge transferring portions, and a part of the horizontal transferelectrodes is overlapped on a portion of the vertical transfer channelregion of the first conductivity that extends in the connection portion,and end portions of the portions of the vertical transfer channel regionof the first conductivity and the vertical well region of the secondconductivity that extend in the connection portion on the side of thehorizontal charge transferring portion are positioned more on the sideof the horizontal charge transferring portion than an end portion of thefinal vertical transfer electrode on the side of the horizontal chargetransferring portion, and are positioned within 1.5 μm from the endportion of the element isolating region of the second conductivity onthe side of the horizontal charge transferring portion.
 2. Thesolid-state imaging device according to claim 1, wherein the horizontaltransfer channel region of the first conductivity is formed so as tohave a lower impurity concentration than that of the vertical transferchannel region of the first conductivity.
 3. The solid-state imagingdevice according to claim 1, wherein the horizontal transfer channelregion of the first conductivity is formed so as to have a largerdiffusion depth than that of the vertical transfer channel region of thefirst conductivity.
 4. The solid-state imaging device according to claim1, wherein the horizontal well region of the second conductivity isformed so as to have a lower impurity concentration than that of thevertical well region of the second conductivity.
 5. The solid-stateimaging device according to claim 1, wherein the horizontal well regionof the second conductivity is formed so as to have a larger diffusiondepth than that of the vertical well region of the second conductivity.6. The solid-state imaging device according to claim 1, wherein theimpurity concentrations of the vertical transfer channel region of thefirst conductivity and the horizontal transfer channel region of thefirst conductivity are set such that, with respect to the horizontaltransfer electrodes arranged so as to overlap the vertical transferchannel region of the first conductivity in the connection portion, achannel potential of the horizontal transfer channel region of the firstconductivity positioned below the horizontal transfer electrodes isdeeper than that of the vertical transfer channel region of the firstconductivity positioned below the horizontal transfer electrodes.
 7. Amethod for producing the solid-state imaging device according to claim1, comprising: forming an ion implantation blocking film on asemiconductor substrate; forming a first photoresist film on the ionimplantation blocking film; patterning the first photoresist film andthe ion implantation blocking film such that the first photoresist filmand the ion implantation blocking film are left on a region to be formedinto an element isolating region of a second conductivity and areremoved from a region to be formed into a vertical transfer channelregion of a first conductivity and a horizontal transfer channel regionof the first conductivity; forming the vertical transfer channel regionof the first conductivity and the horizontal transfer channel region ofthe first conductivity by implanting ions of impurities of the firstconductivity in a surface layer of the semiconductor substrate, andforming a vertical well region of the second conductivity and ahorizontal well region of the second conductivity by implanting ions ofimpurities of the second conductivity below the vertical transferchannel region of the first conductivity and the horizontal transferchannel region of the first conductivity, using the first photoresistfilm and the ion implantation blocking film as a mask; removing thefirst photoresist film and then forming a second photoresist on thesemiconductor substrate; patterning the second photoresist film suchthat the second photoresist is left on the horizontal transfer channelregion of the first conductivity and removed from the vertical transferchannel region of the first conductivity; and implanting further ions ofimpurities of the first conductivity in the vertical transfer channelregion of the first conductivity, using the second photoresist film andthe ion implantation blocking film as a mask.
 8. A method for producingthe solid-state imaging device according to claim 1, comprising: formingan ion implantation blocking film on a semiconductor substrate; forminga first photoresist film on the ion implantation blocking film;patterning the first photoresist film and the ion implantation blockingfilm such that the first photoresist film and the ion implantationblocking film are left on a region to be formed into an elementisolating region of a second conductivity and are removed from a regionto be formed into a vertical transfer channel region of a firstconductivity and a horizontal transfer channel region of the firstconductivity; forming the vertical transfer channel region of the firstconductivity and the horizontal transfer channel region of the firstconductivity by implanting ions of impurities of the first conductivityin a surface layer of the semiconductor substrate using the firstphotoresist film and the ion implantation blocking film as a mask,removing the first photoresist film and then forming a secondphotoresist film on the semiconductor substrate; patterning the secondphotoresist film such that the second photoresist is left on thehorizontal transfer channel region of the first conductivity and removedfrom at least on the vertical transfer channel region of the firstconductivity; forming a vertical well region of the second conductivityby implanting further ions of impurities of the first conductivity inthe vertical transfer channel region and implanting ions of impuritiesof the second conductivity below the vertical transfer channel region,using the second photoresist film and the ion implantation blocking filmas a mask; removing the second photoresist film and the ion implantationblocking film and then forming a third photoresist film on thesemiconductor substrate; patterning the third photoresist film such thatthe third photoresist film is left at least on the vertical transferchannel region of the first conductivity and removed from the horizontaltransfer channel region of the first conductivity; and forming avertical well region of the second conductivity by implanting ions ofimpurities of the second conductivity below the horizontal transferchannel regions using the third photoresist film as a mask.
 9. A methodfor producing the solid-state imaging device according to claim 1,comprising: forming a first photoresist film on a semiconductorsubstrate; patterning the first photoresist film such that the firstphotoresist film is left on a region to be formed into an elementisolating region of a second conductivity and is removed from a regionto be formed into a vertical transfer channel region of a firstconductivity and a horizontal transfer channel region of the firstconductivity; forming the vertical transfer channel region of the firstconductivity and the horizontal transfer channel region of the firstconductivity by implanting ions of impurities of the first conductivityin a surface layer of the semiconductor substrate using the firstphotoresist film as a mask, and forming a vertical well region of thesecond conductivity and a horizontal well region of the secondconductivity by implanting ions of impurities of the second conductivitybelow the vertical transfer channel region of the first conductivity andthe horizontal transfer channel region of the first conductivity;removing the first photoresist film and then forming a secondphotoresist film on the semiconductor substrate; patterning the secondphotoresist film such that the second photoresist is left on a region tobe formed into an element isolating region of the second conductivityand the vertical transfer channel region of the first conductivity andis removed from the horizontal transfer channel region of the firstconductivity; and implanting further ions of impurities of the secondconductivity in the horizontal transfer channel region of the firstconductivity, using the second photoresist film as a mask.
 10. Themethod for producing the solid-state imaging device according to claim9, further comprising implanting ions of impurities of the firstconductivity in the horizontal well region of the second conductivity,using the second photoresist film as a mask.